Pump



A. RAPPL Feb. 15, I944;

PUMP

Filed July 27, 1940 2 Sheets-Sheet 1 mMm mm m mm R @m m% mm Mm l A M 5 m5% Q a PUMP ' Filed July 27, 1940 2 Sheets-Sheet 2 -l/ Z0 9 0 19 J ,1 1d

5 52 15 AA/ro/v 1525 Patented Feb. 15, 1944 PUMIP Anton Rappi, Buffalo,N. Y., assignor to Trico Products Corporation, Buffalo, N. Y.

Application July 27, 1940', Serial No. 347 937 20 Claims.

This invention relates to a pump for use in the generation of fluidpressure.

The novel fluid displacing means of my invention involves fundamentallythe provision of a movable fluid impelling member of novel form inassociation with a pumping chamber whose interior wall is also of novelform whereby the fluid impelling member and the chamber wall cooperateto provide a plurality of pump chambers which are successively expandedand contracted in size by virtue of movement of the impelling member inthe chamber. A primary object. of my invention is to provide a fluiddisplacing pump which will operate in an efficient and continuous mannerand one whose construction is practical and economical.

In one form of my invention the casing of the chamber above mentioned ismounted for to. and fro movement to permit cooperation between theimpelling member and the walls of the pumping chamber in a practical andeflicient manner. In such form the casing for the pump chamber itselfmaycomprise a second piston for a second pumping unit, a suitable casingbeing disposed, about such second piston to complete the second pumpingunit.

In the specific embodiment of my invention which is depicted in thedrawings and described in the ensuing specification the two pumpingunits referred to are provided with separate valving means whereby thefluids pumped by the two pumping units may be of differentcharacteristic from each other. By the application of mechanical skillthe valving arrangement there shown might be modified to'merge thestreams of fluid pumped by the two pumping units in such manner thattheir action would be cumulative and supplementary one to the other.

In pumps constructed according to the teachings of my invention thepumping impulses are,

comparatively speaking, of relatively small amplitude and high frequencywhereby the streams of fluid pumped, whether they be one or twodiffeernt fluids, are nearly constant in volume and not accompanied bypulsating or surging to the extent that such pulsating and surging ispresent in pumps heretofore in practical use.

In the drawings:

Fig. 1 is a vertical cross sectional iew taken along the axis ofrotation of the drive shaft thereof with the wall of the crank case ofan internal combustion engine illustrated fragmentarily;

Fig. 2 is a cross sectional View taken generally along line IIII of Fig.l but with the rotary driving element in cross section;

Fig. 3 is an end view of the device taken fromthe left. as viewed inFig. 1 and with portions broken away to better illustrate the fluidp'assage;

Fig. 4 is a cross sectional view taken along the line'IV-IV of Fig. 1;

Fig. 5 is across sectional view taken along line V-V of Fig. 1;

Fig. 6 is a cross sectional view taken approximately along the line 6-6of Fig. 2

Fig. 7 is a detailed perspective-view of a valving element;

Fig. 8' is a similar View of the opposite side of such valvingelement;and' Fig. 9-- is a fragmentary diagrammatic view similar to Fig. 2 butwith the elements thereof shown in another phase of cycle of operation.

In. the drawings the numeral I9 designates a casing element having awall It and an open side opposite the wall, such open side beingnormally covered by a closure plate; I2 which, with the casing IE1,forms a compartment for housing pumping means. Within such compartmentthere is disposed a piston element t3 which, in the exemplary form,comprises a swinging vane which is pivoted as upon the pin M- which hasits opposite ends supported in the wall I! of the casing Ill and in theclosurerplate l2 respectively. It will be noted from a consideration ofFig. 2 that the end of the piston l3 which is adjacent the pivot pin I lis of relatively short radius struck from the pivot as a center and suchend seats against a portion of the casing 10, which has a like curvatureto provide a constant seal between the piston t3 and the casing H1 atthis point throughout the pivotal movements of the piston.

At its opposite end the piston l3 has a projection i5 whose terminus isvlikewise arcuate and struck from the center of the pivot pin it toengage a similarly curved portion of the interior of the casing in sothat at this point also the piston is constantly in sealing engagementwith the interior of the casing l6. These arcuate engagements togetherwith the fact that the piston 13, in thickness, extends the fulldistance between the wall ll of the casing and the closure plate I 2-,results in the provision of a pair of pump chambers l9 and 20 atopposite sides of the piston as appears in Fig. 2.

The piston I3 is adapted, in a manner which will: presently appear, tooscillate about the pivot pin M to successively and alternately expandand contract the chambers l9 and 2H and suitable means, which willpresently be described, are provided for utilizing such alternateexpansion and contraction for the pumping of fluid. While a swingingvane type of piston has been shown and described, it will appear thatthe principles of my invention may be pursued in struc tures embodying areciprocating piston or one of any other suitable form.

The medial portion of the piston I3 may be formed with a somewhatbulbous enlargement for the reccptionof means forming a second distinctbut associated pumping unit which may, by suitable modification, beutilized to pump additive quantities of the same fluid as is beingpumped by the first pump unit but which, in the illustrated example, isarranged to pump a second and distinct fluid. In the present embodimentof my invention such second pumping unit is utilized for producingalternating movements of the piston I3 for operating the first-describedpumping unit. A chamber for such second pumping unit is formed, asappears best in Fig. 2, by providing an opening in the piston or vane I3as at 24. In the form of the invention which is illustrated, suchopening has substantially parallel side walls joined by curving endwalls. This description of the shape of the opening 22 is approximatelyonly as will presently appear.

The closure plate I2 is provided with a portion 26 which is disposedsubstantially centrally thereof and extends in a direction away from thecasing ID. The portion 26 cooperates to support the entire pump assemblyand, further, provides bearing for a drive shaft 21 for the device. Asviewed in Fig. 1, the right-hand end of the shaft 21 is broken away butthat end is adapted to be connected with any suitable form of drivemeans for rotating the shaft 21. In one embodiment the right-hand end ofthe shaft 21', as viewed in Fig. 1, may be provided with a gear forengagement with a cooperating gear on the camshaft of an internalcombustion engine with which the pumping device is associated. Thesupporting wall 28 which is fragmentarily indicated in Fig. 1 will insuch case be a portion of the crank case of such engine.

A fluid displacing element or piston 29 is secured to the shaft 21 forrotation therewith and to this end the displacing element 29 is formedwith an opening for receiving the shaft 21, such opening beingcounterbored to a larger diameter at its left end, as viewed in Fig. 1,for receiving a valving element 33.

The fluid displacing element 29 has a contour which presents three lobesor protuberances which in the illustrated embodiment are equally spacedabout the element 29, the intermediate portions of the contour of theelement being such that the overall dimension of the element 29 is verynearly constant, considered from various angles in the plane of rotationof the element 29. In one form this end may in general be attained byforming the three equally spaced lobes of relatively small arcs, theside of the element 29 which is opposite each lobe being arcuate andhaving its center of curvature approximately coincident with the centerof curvature of the lobe, although in actual practice certaincompensation must be made for the swinging nature of the alternatingmovement of the piston I3 in the illustrated embodiment.

With the fluid displacing element 29 in the position illustrated in Fig.2, that is with one of its lobes coinciding with the vertical centerline and the other two symmetrically, disposed about said center line,the piston I3 which serves as a pump housing for the fluiddisplacingelement 29 is likewise centrally disposed and the pumpchambers I9 and 20 which the piston I3 forms with the casing I9 are ofequal size, that is they are at midway points in their relativeconditions of expansion and contraction. As the fluid displacing element29 is rotated in a clockwise direction, as viewed in Fig. 2, it will beseen that the lower left-hand lobe of the fluid displacing element 29will move upwardly and to the left, as seen in that figure, while thelower right-hand lobe will move downwardly and likewise to the left,with the other lobe of that figure moving along the upper curved portionof the contour of the opening 24 in the piston I3. Such movement of thefluid displacing element 29 will cause the piston I3 to move to the leftabout its pivot I4 until the lower left-hand lobe of Fig. 2 reaches thehorizontal center line of the axis of rotation of the fluid displacingelement 29 at which time the curved side of the fluid displacing element29 which lies directly opposite this lobe will be in engagement with theright-hand wall of theopening 29. This position represents the extremeleft-hand position of the piston I3 as viewed in Fig. 2 and in thisposition the pump chamber I9 will be in its state of maximum contractionwhile the pump chamber 20 will be in its maximum condition of expansion.

Continued rotation of the fluid displacing element 29 will cause thelobe, which appears at the lower left-hand corner of the piston element3| in Fig. 2, to move upwardly and to the right, while the lobe which isat the top center of the fluid displacing element 29 in Fig. 2 will bythis time engage the right-hand side wall of the opening 29 and movedownwardly and to the right until it in turn reaches a point where itcoincides with the horizontal center line of the axis of rotation of thefluid displacing element 29 at the right-hand sideof the opening 24whereupon the piston I3 will be in its extreme right-hand position andthe pump chamber I9 will be fully expanded and the pump chamber 29 fullycontracted.

Continuous rotation of the piston element 29 will therefore result ineach of the three lobes of the fluid displacing element 29 imparting tothe piston I3 both a left and a right-handmovement during each rotationof the fluid displacing element 29 with the result that each pumpchamber I9 and 29 will be expanded and contracted to its maximum degreethree times during each rotation of the piston element 29, this movementresulting in six complete pump chamber expansion and contraction cyclesper revolution of the fluid displacing element 29.

The manner in which these expanding and contracting pumping movementsare utilized in the displacement of fluid by the provision of suitablevalve and conduit means for the fluid being pumped will now bedescribed.

An axial bore 30 leads from the left end of the shaft, as viewed in Fig.l, to a point substantially medially thereof where it meets a transverseopening 3I which registers with a transverse opening 32 in the bearingportion 26. The openings 39, 3| and 32 cooperate to form a fluiddischarge passage for the pump chambers I9 and 29 in a manner which willpresently appear.

The portion of the shaft receiving opening which is adjacent thecounterbore is provided with oppositely disposed notches as at 35. Thenotches 35 receive a pair of pins 36 which are secured in the shaft 27adjacent its left end and radiate: front oppositessides theienf. It willbe seen; that-the shaftzzl is';to': beassembledinto the,

displacing: element: 2.9:. from thetleft; as; viewed in;

Fig. 12, to. permit: introduction. of. the radiating pins: 36 into" the.notches 35.. 1

Subsequent to the introduction of: the shaft.

27: intothe displacing: element 29 the valving element 33". is disposedinxthe counterbore'v provided therefor in the; displacing. element. Thevalving' element 33 is. cup-shaped: in form: and has a pair ofprotuberanceszatits rim: portion for engagement in theadgiacentends ofthe notches so that when in assembled position the shaft 21', thedisplacin element 29-, and the valving elementSSJ rotateas a unit. Thecup-shapedT-valwing element is shown in detail in Figs. 7 and 8- andcomprises an annular portion 31. and anact as an integralunit in theembodiment of theinvention illustrated inthe drawings."

Theend wall 38' has three equally spaced fluid passages extendingtherethrough. as at $0, and, in

addition, is provided with a blind recess 4"! which comprises threedivergent" arms disposed midway between the several ports No-partof therecess 4| extends through the'endwall' 3S and the radiating arms thereofserve to selectively connect fluid passagesforme-d; in the. wall ll ofthe casing In to coperate. in properly valvin'g the pump chambers l9and" 20' in a manner which will now be described Fluid communication.with; the pump chambers l9 and 20- is gained by'meansof passages 34 andlfiwhich lead therefrom respectively, and, as appears best in Fig. 3;.open respectively injpassages and' 4''!" which terminate. in. ports 48.and 39, respectively. The port's'48 and 4'9. open into. the interiorface of the. Wall H of the casing It]. Disposed between the ports..al8and. 49 and like wise opening into the inner face of. the wall H isaport 51- to which may be connected 2. conduit 52' which will:constitute a" fluid inlet conduit to the pump chambers 18' and 2!};

It has been stated" that the valving element33 rotates with the fluiddisplacing element 29 and the shaft 2-1 and it will therefore appearfrom a consideration of the foregoing description that for a certainperiod during its rotation a fluid passage 40 of the valve element willpass over and be in communication with the port 48 in. the face andduring such period the p umpv of the wall ll chamber 19 will beconnected for exhausting fluid through passages 44 and 4B,.the port 48,and

opening 50, thence through the. bore 30 and the transverse element 3| intheshaft 2?, and through the opening 32. in. the portion 26 of' theclosure plate 12. Obviously. the valving element 33 will be so relatedwith respecttothe displacing element 29 that the foregoing. connectionbetween the port 48 and. the opening 40 is established during movementof the piston E3 to the left, as seen in Fig. 2, to contract thepumpchamber 19.

At the same time the radiating arm of the blind recess 8! which isdisposed opposite the nected by convex faces.

through the port 5 i, the blind recess 4i the port $9 and the passages47 and 45. Continued rotation ofj'the fluid; displacing element 29 andthe valving'element 33 breaksthestated connections and reverses theconnection of the. ports. 48: and.

4-9;so.that.they are connectedto a source of inlet fluid and with theexhaust passages respectively. It will be noted that the respectiveinlet and exhaust connections of the chambers: I 9 and 20 arereversedduring everyone-sixth revolution of the displacing element 29 to providefor proper valving of the. three complete pumping cycles which. areexecuted by each of the pumpcham-.

hers iii and 283 during a single rotation of the shaft 21'; the-fluiddisplacing element 29 and the valving'element 33.

It has already been set forth that the displacing element 29 in theillustrated embodiment, and as is best shown in Fig. 2, is provided withthree lobes or projecting portions which are con- The resultant contouris that of a three-lobedcam with the lobes substantially equally spacedabout the cam surface and the cooperation of the element 29 as a drivemember for the piston !3 has previously been described. As itsdesignation implies, however, the fluid displacing element 29 has a dualfunction and serves also,

and communicate with intake and discharge passages 6! and 62respectively which extend'through the-piston element l3 and terminate atthe adjacent face of the closure plate [2. or non-adjacent side of theclosure plate I 2 is shown in Fig, 4, but the somewhat rectangularinletand discharge passages 63 and 64' respectively which extend fromthe piston engaging face of the closure plate I2 through such closureplate may be seen in Fig. '4 and terminate in variously formed elongateopeningsnumbered 65, 65, 6'5 and 63. The last mentioned openings arespecially formed to cooperate with a discharge fluid and inlet fluidcollecting plate 10, shown in detail in 5, which is provided for mergingfluid passing 6t and also for merging the fluid passing through the twoinlet passages 63 to provide a single ultimate discharge passage and asingle ultimate inlet passage adjacent the wall 28 of the internal.combustion engine crankcase referred. to previously."

To this end, the collecting plate 10 has, in the surface which abuts theclosure plate l2, two inlet openings ii and 12 which communicaterespectively with portions of the elongate openings 68 and 66respectively, which in turn lead from the inlet ports 63. merged at theside of the collecting-plate, which is away from the closure plate l2,by a depression M which is best shown in Fig; 5.

In a similar manner, the face of the collecting platelmwhich is adjacentto the closure plate 12,

3. iven. opening 4i); servestobridge amtconnectthe: port: and" the port51;, the latter: ofwhich: is connected with a fluid source so thatfluidiflowsv into the then enlarging pump. chamber 2i]v in cooperation withthe opening 24 of the piston I3, as a second pumping. unit; 7 Eachconvex face of the displacing ele-' ment 2% cooperates with changingportions of the p the piston element l3 to the parts in the positionillustrated inv pairs of alternately disposed I intake and dischargeports 59 and respectively lead from the interior Wall .of the opening24.

The reverse through the two discharge passages The openings H and 12 areis provided with a-pair of openings I5 and I5 which register withportions of the elongate openings 65 and 6'! respectively which leadfrom the discharge passages 6 The openings I5 and I6 are also merged atthe face of the plate III, which is away from the closure plate I2, by adepression 'I'I.- Fluid inlet and discharge conduits will be associatedwith the wall 28 of the crank case of the engine in such manner as tocommunicate with any part of the depressions I I and 11 respectively.

The casing II], the closure plate I2, and the fluid collecting plat ID,are held in assembled position with respect to each other with aplurality of screws Bil and the entire assembly may be secured againstthe wall 28 of an internal combustion engine crank case by means ofscrews BI.

The operation of the displacing element 29 in the opening 24 of thepiston I3 with respect to its fluid displacing function will now bedescribed. The pumping chambers 55, 56 and 51 previously referred to aretransitory in their nature and are referred to merely as a convenientstarting point in the description of operation. Ina sense they come intobeing and perform a singlepumping cycle of intake and exhaust, thencease to exist, giving way to other pumping chambers inthe rotation ofthe displacing element 29 inthe chamber 2 The opening 2 6 in the pistonI3 is developed or generated from the displacing element 29 and is soformed that its opposite side walls, as seen in Fig. 2, are alwayscontacted by the displacing element 29, Either a lobe or an intermediatecurving face of the displacing element 29 is always in abutment witheach of the approximately straight side walls of the opening 2d.Further, ,each of the three lobes of the displacing element 25 traversesthe curving portions at the upper and lower ends of the opening it andremains in frictional engagement therewith throughout its travel alongboth the upper and lower curving portions from one side wall of theopening 24 to the other.

' With the displacing element 29 in the position I in which it isillustrated in Fig. 2 and rotating in a clockwise direction, the pumpingchamber 55 is being enlarged and fluid is being drawn thereinto throughthe upper left-hand inlet port 53. At the same time the pumping chamber56 is being contracted and fluid is being expressed therefrom throughthe upper right-hand exhaust port 69. At this same point in the cycle ofoperation, the pumping chamber 51 has been filled with fluid through thelower right-hand inlet port 59 and such fluid is being transferred to apoint where it will be expressed from the chamber 57 through the lowerleft-hand exhaust port 60.

Fig. 9 is a diagrammatic view similar to Fig. 2 but with the fluiddisplacing element 29 in a position in advance of that illustrated inFig. 2, and it will be noted therefrom that pumping chamber is ofgreater area than in Fig. 2, the pumping chamber 56 is approaching astate of total exhaustion, the pumping chamber 51 has moved to aposition of communication with the lowerleft-hand exhaust port and fluidis being expressed therefrom, and a new pumping chamber 35 has beencreated at the lower right-hand portion of the chamber 24 and is incommunication withthe lower right-hand inlet port 59 and drawing fluidtherethrough.

As the approaching lobe of the displacing element29 reaches the upperright-hand exhaust port 60, the pumping chamber 56 is in a state oftotal exhaustion and in fact ceases to exist, giving place to the newpumping chamber 85. In subsequent rotation of the displacing element 29,the pumping chamberf5'! is likewise totally compressed when the nextsucceeding lobe of the displacing element '29 reaches the lower lefthandport 60, in turn giving way to a new pumping chamber which forms at theupper left-hand intake 59 in the same manner as in the case of thepumping chamber 85. It will be noted from the foregoing that at someperiods in the cycle of rotation of the displacing element 29 in theformance of the other in that the portion of the oil which is the mediumbeing pumped by the displacing element 29 is forced through a groove 81formed in the faceof the piston I3 which is adjacent the wall II of thecasing I0, such oil traveling along the bearing of the pivot pin I4 andsubsequently outward through a groove 88 formed in the opposite face ofthe piston I3 whereupon the oil serves to lubricate and provide a fluidseal for the piston I3 at its opposite point of arcuate engagement withthe casing II).

The exhaust passages 62 extend entirely through the piston I3 and at thewall II of the casing I0 intersect a circular oil groove 90 formed inthe face of the piston I3 to further assist in the provision of an oilseal for the pumping unit formed by the piston I3 and the casing Ill.The inlet passages 6| stop short of the wall II of the casing II) toprevent withdrawal of sealing lubricant therefrom. In the embodimentillustrated in the drawings the external pumping unit comprising thepiston I3 and the casing I0 is used to create a partial vacuum, usuallyfor the operation of the automotive accessories, and the air pumpedthereby isexhausted into the internal combustion engine crank case. Inthis way sealing lubricant which passes from the oil pumping unit to theair pumping unit is ultimately returned to the engine crank case.

Various modifications may be made in the structure which is described byway of example without departing from the spirit or scope of theinvention which is tobe considered as limited only by the appendedclaims.

I claim:

1. In a fluid pump, a casing having an open ing therein comprising acontinuous non-circular wall, a rotatable piston comprising a camlikeelement disposed in said opening for rotation therein on an axiscoincident with its geometric center and having three lobes, the wall ofsaid opening being so formed that the three lobes of the piston aresubstantially permanently in contact with said wall during rotation ofsaid piston to form a plurality of pumpmg chambers, means permittinglimiting body movement of said casing but preventing rotation thereof,said casing being formed with inlet and exhaust passages, the rotationof said piston being adaptedto successively expand said pumping chambersin the region of the inlet passages and contract said pumping chambersin the region of the exhaust passages to pump fluid in a substantiallycontinuous flow.

-2. ln a fluid pump, a casing having an opening therein comprising acontinuous non-circular wall, a rotatable piston therein comprising acam-like element disposed in said opening for rotation therein about afixed axis and having three lobes, the continuous wall of said openingforming a closed figure having substantially parallel side wall portionsand curving end wall portions connecting the side wall portions,said-casing being mounted for guided movement transverselyito saidparallel side wall portions and said opening being so shaped andproportioned with respect to the lobes of the piston that the threelobes of the piston are substantially permanently in contact with saidwall during rotation of said piston to form a plurality of pumpingchambers, said casing being formed with inlet and exhaust passages,

the rotation of said piston being adapted to the side opposite such lobeapproximately 0011- centric and the wall of ,said opening being soformed that the three lobes of the piston are substantially permanentlyin contact with" said 'wall during rotation of said piston to form aplurality of pumping chambers, means permitting limited body movement ofsaid casing but preventing rotation thereof, said casing being formedwith inlet and exhaust passages, {the rotation of said pistonbeingadapted to successively expand said pump chambers in the region ofthe inlet passages and contract said pumping chambers in the region ofthe exhaust passages to'pu'mp fluid 'in a substantially con- 4.'In afluid pump, a-casing having an opening therein comprising a continuousnon-circular wall, a rotatable piston therein comprising a cam-likeelement disposed in said opening for rotation therein and having threelobes, the continuous mm of said opening forming a closed figure havingsubstantially parallel side wall portions-and curving end wall portionsconnecting the side wall portions and the piston having three arcuatelobes and three arcuate sides connecting the lobes with the radius ofeach lobe and the radius of the side opposite such lobe approximatelyconcentric, said casing being the region of the exhaust passages to pumpfluid in a substantially continuous flow.

- 5. Ina fluid pump, a casing having an opening therein comprising acontinuous non-circular wall, a rotatable piston therein comprising acam-like element disposed in said opening for rotation therein on anaxis coincident with its geometric vcenter and having a plurality oflobes of odd number, the continuous wall of said opening forming aclosed figure having substantially parallel side wall portions andcurving end wall portions connecting the said wall portions and thepiston having arcuate lobes and arcuate sides connecting the lobes withthe radius-of each lobe and the radius of the side opposite such lobeapproximately concentric, said casing being mounted for guided movementtransversely to said ,paralle'l side wall portions and said openingbeingso shaped and proportioned with respect to the lobes of the pistonthat the lobes of the piston are substantially permanently incontactwith said wall during rotation of said piston to form a pluralityof pumping chambers, meanssupporting said casing for limited bodymovement but preventing rotation thereof, said casing being formed withinletandexhaust passages, vthe rotation of said piston being adapted tosuccessively expandsaid pump chambers in theregion of the inlet passagesand contract said pumping chambers in the region of the exhaustpassagesto pump fluid in a substantially continuous flow.

6. In a fluid pump, a 'movably mounted pump oasing, a piston rotatableon an axis coincident with its goemetric center comprising a cam havingthree lobes-said casing having an opening therein having a continuousnon-circular wall, saidrotatable-piston being. disposed in said openingfor rotation therein, said opening being so formed that the-three lobesof said piston are substantially permanently in contact with said Wallduring'rotation of said piston to form a' plurality of pumping chambers,said wall being'formed with inlet and exhaust passages, the rotation ofsaid pistonabeing adapted to successively expand said pumping chambersin the regionof, the inlet passages andcontract said pumping chambersthe regioniof the exhaust passages to pump fluid in a substantiallycontinuous flow.

7. In a fluid pump, a casing and a piston disposed for to and fromovement therein, fluid conduit means for communication with theinterior of said casing at opposite sides of said piston and valve meansfor controlling such communication, and a second pump comprising anopening formed in said piston and having a continuous non-circular wall,and a rotatable piston comprising a cam-like element having three lobes,the continuous wall of said openingbeing so formed that the three lobesof said rotatable "piston are substantially permanently in contact withsaid wall during rotation of said piston to form a plurality'of pumpingchambers and toimpart-to 'and'fro movement tosaid first mentionedpistonduring rotationof the rotatable piston, the first mentioned piston beingformed with inlet and exhaust passages for said ing being so shaped andproportioned with respect to the lobes of the piston that the threelobes of the piston are substantially permanently in contact with saidwall during rotation of said piston to form a plurality of pumpingchambers, said casing being formed with inlet and exhaust passages, therotation of said piston being adapted to successively expand said pumpchambers in the region of the inlet passages and contract said pmnpingchambers in the region of the exhaust passages to pump fluid in asubstantially continuous fiow.

9. In a fluid pump, an oscillatable casing having an opening thereincomprising a continuous non-circular wall, a rotatable piston thereincomprising a cam-like element disposed in said opening for rotationtherein and having a plurality of lobes of odd number, the, continuousWall of said opening forming a closed figure having substantiallyparallel side wall portions and curving end wall portions connecting theside wall portions and the piston having arcuate lobes and arcuate sidesconnecting the lobes with the radius of each lobe and the radius of theside opposite such lobe approximately concentric, said casing beingoscillatable in a direction transverse to said parallel side wallportrons and said opening being so shaped and proportioned with respectto. the lobes of the piston that the lobes of the piston aresubstantially permanently in contact with said wall during rotation ofsaid piston to form a plurality of pumping chambers, said casing beingformed with inlet and exhaust passages, the rotation of said pistonbeing adapted to successively expand said pump chambers in the region ofthe inlet passages and contract said pumping chambers in the region ofthe exhaust passages to pump fluid in a substantially continuous flow.

10. In a fluid pump, mounting said casing for limitedj pivotal movementabout a fixed axis, said casing having an opening therein comprising acontinuous noncircular wall, a piston rotatable about a fixed axis andcomprising a cam-like element disposed in said opening for rotationtherein and having three lobes, the wall of said Opening being so formedthat the three lobes of the piston are substantially permanently incontactwith said wall during rotation of saidpiston to form a pluralityof pumping chambers, said casing being formed with inlet and exhaustpassages, the rotation of said piston being adapted to successivelyexpand said pump chambers in the region of the inlet passages andcontract said a pumping chambers in the region of the exhaust passagesto pump fluid in a substantially continuous fiow.

11. In a fluid pump, a casing and means mounting said casing for limitedpivotalmovement about a fixed axis, said casing having-an openingtherein comprising a continuous noncircular wall, a piston thereinrotatable about a fixed axis and comprising a cam-like element disposedin said opening for rotation therein a casing vand meansand having threelobes, the continuous wall of said opening forming a closed figurehaving substantially parallel side wall portions and curving end wallportions connecting the sidewall portions and the piston having threearcuate lobes and three arcuate sides connecting the lobes with theradius of each lobe and the radius of the side opposite such lobeapproximately concentric, said opening being so shaped and proportionedwith respect to the lobes of the piston that the three lobes of thepiston are substantially permanently in contact with said wall duringrotation of said piston to form a plurality of pumping chambers, saidcasing being formed with inlet and exhaust passages, the rotation ofsaid piston being adapted to suecessively expand said pump chambers inthe region of the inlet passages and contract said pumping chambers inthe region of the exhaust passages to pump fluid in a substantiallycontinuous fiow.

12. In a fiuid pump, a casing and a rotatable piston therein, saidcasing having an opening for receiving said piston, said opening, asviewed along the axis of rotation of the piston, having substantiallyparallel side wall portions and curving end wall portions connectingsaid side wall portions to form an uninterrupted wall surface, saidcasing being mounted for movement in a direction transverse with respectto said parallel side wall portions, said rotatable piston having threelobes, said opening and said piston being so proportioned that the threelobes are adapted to traverse said uninterrupted wall surface insubstantially continuous contact therewith, said lobes cooperating withsaid wall surface to form pump chambers between successive lobes, andinlet and exhaust passages formed in said casing and communicating withsaidpump chambers in the region of their successive expansion andcontraction.

13. In a fluid pump, a casing and a piston disposed therein, meansmounting said piston for pivotal rocking movement about a fixed axis,

fluid conduit means for communication with the interior of said casingat opposite sides of -said piston and valve means. for controlling suchcommunication, and a second pump comprising an opening formed in saidpiston and having a continuous non-circular wall, and a rotatable pistoncomprising a cam-like element having three lobes, the continuous wall ofsaid opening having parallel side wall portions engageable by saidrotating piston to impart alternating pivotal movement to said firstmentioned piston, said rotatable piston and said opening being so formedthat the three lobes of the piston are substantially permanently incontact with said wall during rotation of said piston to form aplurality of pumping chambers,,the first mentioned piston being formedwith inlet and exhaust passages, the rotation of said rotatable pistonbeing adapted to successively expand said'pump chamber in the region ofthe inlet passages. and contract said pumping chambers in the region ofthe exhaust passages. I 14. In a fluid pump, a casing having an openingtherein comprising a'continuous non-circular wall, a rotatable pistoncomprising a camlike element disposed in said opening for rotationtherein on an axis coincident with its geometric center and having threelobes, the wall of said opening being so formed that the three lobes ofthe piston are substantially permanen'tly in contact with said wallduring r'ota tion of said piston to form a plurality of pumpingchambers, means supporting said casing for guided to and fro movement byengagement of the lobes of the piston with the wall of said opening,said casing being formed with inlet and exhaust passages, the rotationof said piston being adapted to successively expand said pumpingchambers in the region of the inlet passages and contract said pumpingchambers in the region of the exhaust passages to pump fluid in asubstantially continuous flow.

15. In a fluid pump, a casing having an opening therein comprising acontinuous non-circular wall, a rotatable piston comprising a camlikeelement disposed in said opening for rotation therein on an axiscoincident with its geometric center and having three lobes, saidopening having substantially parallel side wall portions and curving endwall portions connecting said side wall portions to form a substantiallyuninterrupted wall surface and said opening being so formed that thethree lobes of the piston are substantially permanently in contact withsaid wall during rotation of said piston to form a plurality of pumpingchambers, means supporting said casing for guided to and fro movement byengagement of the lobes of the piston with the side walls of saidopening, said casing being formed with inlet and exhaust passages, therotation of said piston being adapted to successively expand saidpumping chambers in the region of the inlet passages and contract saidpumping chambers in the region of the exhaustpassages to pump fluid in asubstantially continuous flow.

16. In a fluid pump, a casing having an opening therein comprising acontinuous non-circular wall, a rotatable piston comprising a camlikeelement disposed in said opening for rotation therein on an axiscoincident withits geometric center and having three lobes, the wall ofsaid opening being so formed that the three lobes of the piston aresubstantially permanently in contact with said wall during rotation ofsaid piston to form a plurality of pumping chambers, means supportingsaid casing for oscillation by engagement of the lobes of the pistonwith the wall of said opening, said casing being formed with inlet andexhaust passages, the rotation of said piston being adapted tosuccessively expand said pumping chambers in the region of the inletpassages and contract said pumping chambers in the region of the exhaustpassages to pump fluid in a substantially continuous flow.

17. In a fluid pump, a casing having an opening therein comprising acontinuous non-circular wall, a rotatable piston comprising a camlikeelement disposed in said opening for rota tion therein on an axiscoincident with its geometric center and having three lobes, saidopening having substantially parallel side wall portions and curving endwall portions connecting said side wall portions to form a substantiallyuninterrupted wall surface and said surface being so formed that thethree lobes of the piston are substantially permanently in contact withsaid wall during rotation of said piston to form a plurality of pumpingchambers, means supporting said casing for oscillation by engagement ofthe lobes of the piston with the wall of said opening, said casing beingformed with inlet and exhaust passages, the rotation of said pistonbeing adapted to successively expand said pumping chambers in the regionof the inlet passages and contract said pumping chambers in the regionof the exhaust passages to pump fluid in a substantially continuousflow.

18. In a fluid pump, a casing mounted for guided to and fro movement, arotatable piston comprising a cam-like element having three lobes, saidcasing having an opening receiving said piston for rotation therein, thewall of said opening having opposed side walls spaced a distance equalto the greatest diamctrical dimension across said piston whereby saidcasing is moved to and fro by rotation of said piston therein, the endwalls of said opening being generated by the movement of the pistonlobes therealong during the to and fro movement of said casing, wherebythe three lobes of the piston are substantially permanently in contactwith said wall during rotation of said piston to form a plurality ofpumping chambers, said casing being formed with passages for taking inand exhausting fluid, the rotation of said piston being adapted tosuccessively expand and contract said pumping chambers to pump fluid ina substantially continuous flow.

19. In a fluid pump, a rotatable piston comprising a cam-like elementhaving three lobes, a casing having an opening receiving said piston forrotation therein and having av pivot spaced from said opening topermit'oscillation of said casing, the wall of said opening havingopposed side walls spaced a distance equal to the greatest diametricaldimension across said piston whereby said casing is moved to and fro byrotation of said piston therein, the end walls of said opening beinggenerated by the movement of the piston lobes therealong during the toand fro movement of said casing, whereby the three lobes of the pistonare substantially permanently in contact with said Wall during rotationof said piston to form a plurality of pumping chambers, said casingbeing formed with passages for taking in and exhausting fluid, therotation of said piston being adapted to successively expand andcontract said pumping chambers to pump fluid in a substantiallycontinuous flow.

20. In a fluid pump, a casing mounted for guided to and fro movement, arotatable piston comprising a cam-like element having three arcu-atelobes and three arcuate sides connecting the lobes with the radius ofeach lobe and the radius of the side opposite such lobe approximatelyconcentric, said casing having an opening receiving said piston forrotation therein, the wall of said opening having opposed side wallsspaced a distance substantially equal to the sum of the said two radiiwhereby said casing is moved to and fro by rotation of said pistontherein, the end walls of said opening being generated by the movementof the piston lobes therealong during the to and fro movement of saidcasing whereby the three lobes of the piston are substantiallypermanently in contact with said wall during rotation of said piston toform a plurality of pumping chambers, said casing being formed withpassages for taking in and exhausting fluid, the rotation of said pistonbeing adapted to successively expand and contract said pumping chambersto pump fluid in a substantially continuous flow.

ANTON RAPPL.

